Gabriele Casazza1, Florian C Boucher2,3, Luigi Minuto4, Christophe F Randin5, Elena Conti2. 1. DISTAV, University of Genoa, Corso Europa 26, I-16132 Genoa, Italy gabriele.casazza@unige.it. 2. Department of Systematic and Evolutionary Botany and Botanic Garden, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland. 3. Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa. 4. DISTAV, University of Genoa, Corso Europa 26, I-16132 Genoa, Italy. 5. Department of Ecology & Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland.
Abstract
BACKGROUND AND AIMS: Polyploidization plays a key role in plant evolution. Despite the generally accepted 'minority-cytotype exclusion' theory, the specific mechanisms leading to successful establishment and persistence of new polyploids remain controversial. The majority of newly formed polyploids do not become established, because they are less common, have fewer potential mates or may not be able to compete successfully with co-occurring progenitors at lower ploidy levels. Changes in floral traits and ecological niches have been proposed as important mechanisms to overcome this initial frequency-dependent disadvantage. The aim of this study was to determine whether dodecaploids of the heterostylous P. marginata differ from their hexaploid progenitors in P. marginata and P. allionii for selected floral traits and ecological preferences that might be involved in establishment and persistence, providing a possible explanation for the origin of polyploidized populations. METHODS: Floral morphological traits and ecological niche preferences among dodecaploids and their hexaploid progenitors in P. marginata and P. allionii ,: all restricted to the south-western Alps, were quantified and compared KEY RESULTS: Differences in floral traits were detected between dodecaploids and their closest relatives, but such differences might be too weak to counter the strength of minority cytotype disadvantage and are unlikely to enable the coexistence of different cytotypes. Furthermore, the results suggest the preservation of full distyly and no transition to selfing in dodecaploids. Finally, dodecaploids occur almost exclusively in environments that are predicted to be suitable also for their closest hexaploid relatives. CONCLUSIONS: In light of the results, P. marginata dodecaploids have probably been able to establish and persist by occupying geographical areas not yet filled by their closest relatives without significant evolution in their climatic and pollination niches. Dispersal limitation and minority-cytotype exclusion probably maintain their current range disjunct from those of its close relatives.
BACKGROUND AND AIMS: Polyploidization plays a key role in plant evolution. Despite the generally accepted 'minority-cytotype exclusion' theory, the specific mechanisms leading to successful establishment and persistence of new polyploids remain controversial. The majority of newly formed polyploids do not become established, because they are less common, have fewer potential mates or may not be able to compete successfully with co-occurring progenitors at lower ploidy levels. Changes in floral traits and ecological niches have been proposed as important mechanisms to overcome this initial frequency-dependent disadvantage. The aim of this study was to determine whether dodecaploids of the heterostylous P. marginata differ from their hexaploid progenitors in P. marginata and P. allionii for selected floral traits and ecological preferences that might be involved in establishment and persistence, providing a possible explanation for the origin of polyploidized populations. METHODS: Floral morphological traits and ecological niche preferences among dodecaploids and their hexaploid progenitors in P. marginata and P. allionii ,: all restricted to the south-western Alps, were quantified and compared KEY RESULTS: Differences in floral traits were detected between dodecaploids and their closest relatives, but such differences might be too weak to counter the strength of minority cytotype disadvantage and are unlikely to enable the coexistence of different cytotypes. Furthermore, the results suggest the preservation of full distyly and no transition to selfing in dodecaploids. Finally, dodecaploids occur almost exclusively in environments that are predicted to be suitable also for their closest hexaploid relatives. CONCLUSIONS: In light of the results, P. marginatadodecaploids have probably been able to establish and persist by occupying geographical areas not yet filled by their closest relatives without significant evolution in their climatic and pollination niches. Dispersal limitation and minority-cytotype exclusion probably maintain their current range disjunct from those of its close relatives.
Authors: Mariska te Beest; Johannes J Le Roux; David M Richardson; Anne K Brysting; Jan Suda; Magdalena Kubesová; Petr Pysek Journal: Ann Bot Date: 2011-10-31 Impact factor: 4.357
Authors: Filip Kolár; Magdalena Lucanová; Petr Vít; Tomás Urfus; Jindrich Chrtek; Tomás Fér; Friedrich Ehrendorfer; Jan Suda Journal: Ann Bot Date: 2013-04-14 Impact factor: 4.357
Authors: Mariana Castro; João Loureiro; Albano Figueiredo; Miguel Serrano; Brian C Husband; Sílvia Castro Journal: Front Plant Sci Date: 2020-03-19 Impact factor: 5.753